Abstract:
Climate extreme indices in Tanzania for the period 1961-2015 are analyzed
using quality controlled daily rainfall, maximum and minimum temperatures
data. RClimdex and National Climate Monitoring Products (NCMP) software
developed by the commission for Climatology of the World Meteorological
Organization (WMO) were used for the computation of the indices at the respective
stations at monthly and annual time scales. The trends of the extreme
indices averaged over the country were computed and tested for statistical
significance. Results showed a widespread statistical significant increase in
temperature extremes consistent with global warming patterns. On average,
the annual timescale indicate that mean temperature anomaly has increased
by 0.69˚C, mean percentage of warm days has increased by 9.37%, and mean
percentage of warm nights has increased by 12.05%. Mean percentage of
cold days and nights have decreased by 7.64% and 10.00% respectively. A
non-statistical significance decreasing trends in rainfall is depicted in large
parts of the country. Increasing trend in percentage of warm days and warm
nights is mostly depicted over the eastern parts of the country including areas
around Kilimanjaro, Dar-es-Salaam, Zanzibar, Mtwara, and Mbeya regions.
Some parts of the Lake Victoria Basin are also characterized by increasing
trend of warm days and warm nights. However, non-statistical significant decreasing
trends in the percentage of warm days and warm nights are depicted
in the western parts of the country including Tabora and Kigoma regions and
western side of the lake Victoria. These results indicate a clear dipole pattern
in temperature dynamics between the eastern side of the country mainly influenced
by the Indian Ocean and the western side of the country largely influenced
by the moist Congo air mass associated with westerly winds. The results
also indicate that days and nights are both getting warmer, though, the
warming trend is much faster in the minimum temperature than maximum
temperature.
